Bias-Field-Dependent Impedance and Phase Characterization of a Ferroelectric Liquid Crystals Relevant to Display Applications

Abstract

Phase transition and dielectric relaxation dynamics of a ferroelectric liquid crystal (FLC) material were investigated across the SmC*–N* phase transition using differential scanning calorimetry (DSC) and impedance spectroscopy under applied DC bias fields. Dielectric spectra recorded under DC bias exhibit anomalous low-frequency behavior in the vicinity of the SmC*–N* transition. A pronounced enhancement of low-frequency dielectric absorption is observed at low DC bias fields, followed by suppression at higher bias fields near ~72 °C, accompanied by the presence of the conventional Goldstone mode at slightly higher frequencies. The dielectric response over a wide temperature range, analyzed using a Cole–Cole–modified Debye model in both biased and unbiased conditions, reveals significant variations in the relaxation parameters. The low-frequency relaxation process close to the SmC*–N* transition is attributed to the combined contributions of the Goldstone mode and domain-related dynamics, as evidenced by the anomalous DC bias dependence of the dielectric parameters. The temperature dependance of relaxation parameters under DC bias exhibits conventional 
Goldstone-mode-like behavior due to suppressed domains and field-induced alignment of the spontaneous polarization.